This is a renewal application for support of ongoing research on the use of in vivo synchronization to improve tumor chemotherapy. On the basis of previous success in achieving good synchronization of cells in vivo (crypt cells on the lining epithelium of the small intestine, basal cells of the esophagus), we now propose to study the chemotherapy of metastatic growth after in vivo synchronization. Pulmonary metastases from a transplantable colon carcinoma of mice will be studied after removal of the primary tumor. Prevention and therapy of metastases will be attempted through a combination of chemotherapy and in vivo synchronization.